Warmth may relieve pain, relax muscle spasms, increase circulation, and help heal a wound. Moist warmth is more effective in relieving muscle pain than dry warmth. Once swelling is gone, usually within 48 to 72 hours after the injury, warmth is usually used to provide pain relief.
For an eye injury, use either of the following methods:
Commercial hot packs are not recommended. They are often too heavy and bulky to use near the eye. Also, if a commercial hot pack leaks, chemicals from the bag might get in the eye.
WebMD Medical Reference from Healthwise